Obviously sometimes the updates are fixing real critiques of earlier editions. Those are good. But many times it is “fixing” critiques along the line of “cut out advanced material because it is too much to cover in 1 semester.” Makes sense in an academic context, but not for professionals like you and me that are looking for that kind of stuff.

Books also tend to become more sparse on the page, and with more pointless “illustrative” stock photos that add nothing and take up page real estate (leading to more advanced topics being dropped to reclaim space), but make the book seem more approachable to undergraduates.

Generally applies more to physics, chemistry, and math books than computer science, but it is a general phenomenon.